Devices for controlling non-thermal plasma emitters

ABSTRACT

An AC power supply drives and controls an array of non-thermal plasma emitters at desired frequencies at a controlled power level. The power supply comprises a step-up transformer, a balanced driver, and a controller. The transformer operates at the resonant frequency of the combined capacitance of the array and the cable connecting the array to the power supply. The power into the array is monitored by the controller and can be adjusted by the user. The balanced driver may be driven directly by the controller. The controller monitors the phase relationship between the transformer primary winding voltage and the gate drive voltage, and adjusts the drive frequency to resonance. Alternatively the balanced driver is configured as an oscillator which drives the transformer at resonance by default. A signal from the transformer driver generates an interrupt to the controller for synchronizing current and voltage measurements for power control.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/235,517 filed Sep. 30, 2015 and is a continuation-in-part ofco-pending U.S. patent application Ser. No. 15/055,028 filed Feb. 26,2016. Both aforementioned applications are incorporated by referenceherein in their entirety.

FIELD OF INVENTION

The present invention relates to a device used to drive non-thermalplasma emitters and control the emitted plasma for use in plasmamedicine including therapeutic and diagnostic applications.

BACKGROUND

Plasma is an ionized state of matter known for its cleaning,decontaminating, sterilizing, antimicrobial and healing properties whenapplied to an inanimate surface or to tissue. Plasma can be created whenenergy is applied to a substance. As energy input is increased the stateof matter changes from solid, to liquid, to a gaseous state. Ifadditional energy is fed into the gaseous state, the atoms or moleculesin the gas will ionize and change into the energy-rich plasma state, orthe fourth fundamental state of matter.

There are two types of plasma, thermal and non-thermal, which is alsoknown as cold plasma. Thermal plasmas are in thermal equilibrium, i.e.the electrons and the heavy particles are at the same temperature.Current technologies create thermal plasma by heating gas or subjectingthe gas to a strong electromagnetic field applied with a generator. Asenergy is applied with heat or electromagnetic field, the number ofelectrons can either decrease or increase, creating positively ornegatively charged particles called ions. Thermal plasma can be producedby plasma torches or in high-pressure discharges. If thermal plasma isused in treating a material or surface sensitive to heat, it can causesignificant thermal desiccation, burning, scarring and other damage.

In order to mitigate such damage, methods and devices have been createdfor applying non-thermal plasma to heat-sensitive materials andsurfaces. Whereas in thermal plasmas the heavy particles and electronsare in thermal equilibrium with each other, in non-thermal plasmas theions and neutrals are at a much lower temperature (sometimes as low asroom temperature) than the electrons. Non-thermal plasma usually canoperate at less than 104° F. at the point of contact. Thus non-thermalplasmas are not likely to damage human tissue.

To create non-thermal plasma, a potential gradient is applied betweentwo electrodes. Typically the electrodes are in an environment of afluid such as helium, nitrogen, heliox, argon, or air. When thepotential gradient between the high voltage electrode and groundedelectrode is large enough, the fluid between the electrodes ionizes andbecomes conductive. For example, in the plasma pencil a dielectric tubecontains two disk-shaped electrodes of about the same diameter as thetube, separated by a small gap. The disks are perforated. High voltageis applied between the two electrodes and a gas mixture, such as heliumand oxygen, is flowed through the holes of the electrodes. When thepotential gradient is large enough, a plasma is ignited in the gapbetween the electrodes and a plasma plume reaching lengths up to 12 cmis discharged through the aperture of the outer electrode and into thesurrounding room air. The plume can be used to treat surfaces byscanning it across the surface.

Plasma systems requiring forced gas can be very large and cumbersome,requiring the use of gas tanks to supply the necessary fluid to createthe plasma. Another disadvantage is that there is only a narrow contactpoint between the plasma plume and the surface that it comes intocontact with. Typically, plumes are usually on the order of 1 cm indiameter. This makes treating larger areas time-consuming and tedious,since the contact point has to be moved back and forth across the areato be treated. The uniformity of treatment across the treatment area maybe difficult to control.

Another commonly used method for creating non-thermal plasma is thedielectric barrier discharge (“DBD”), which is the electrical dischargeresulting after high voltage is applied between two electrodes separatedby an insulating dielectric barrier. DBD is a practical method ofgenerating non-thermal plasma from air at ambient temperature and comesin several variants. For example, a volume dielectric barrier discharge(“VDBD”) occurs between two similar electrodes with a dielectric barrieron one electrode, and the electrodes facing each other. A VDBD islimited by the space between the two electrodes, the size of theelectrodes, and cannot conform to different surface topographies. Asurface dielectric barrier discharge (“SDBD”) can occur between oneelectrode and a surface such as skin, metal, or plastic. In a specificexample of SDBD, known as a floating electrode dielectric barrierdischarge (“FE-DBD”) variation, one of the electrodes is protected by adielectric such as quartz and the second electrode is a human or animalskin or organ. In the FE-DBD setup, the second electrode is not groundedand remains at a floating potential. A SDBD treatment area is limited bythe electrodes' size, and like the VDBD, it cannot conform to thesurface the electrode comes into contact with. In current SDBDtechnologies there is only a single contact point between the plasmaplume and the surface that it comes into contact with.

Another type of non-thermal plasma is known as corona discharge, whichis an electrical discharge brought on by the ionization of a fluidsurrounding a conductor that is electrically charged. Corona dischargesoccurs at relatively high-pressures, including atmospheric pressure, inregions of sharply non-uniform electric fields. The field near one orboth electrodes must be stronger than the rest of the fluid. This occursat sharp points, edges or small diameter wires. The corona occurs whenthe potential gradient of the electric field around the conductor ishigh enough to form a conductive region in the fluid, but not highenough to cause electrical breakdown or arcing to nearby objects. Theionized gas of a corona is chemically active. In air, this generatesgases such as ozone (O₃) and nitric oxide (NO), and in turn nitricdioxide (NO₂). Ozone is intentionally created this way in an ozonegenerator, but otherwise these highly corrosive substances are typicallyobjectionable because they are highly reactive. It would be desirable totake advantage of the reactive nature of these gas molecules.

Beyond generating the non-thermal plasma, it would be desirable to beable to control the plasma so that it can be used for beneficialpurposes. It would be desirable to control the length of time the plasmais generated, the power level of the plasma, and to modulate thefrequency and wave form of the plasma. Specific modulation frequenciesare correlated to the killing of specific microorganisms, includingforms of bacteria, virus, fungus, and mold. Therefore it would bedesirable to be able to control such pulse frequency of the plasma too.In this way a plasma can be used to produce biological effects beyondthose produced by the reactive species. To ensure the emitted plasmameets desired parameters, it would be useful to limit the emissions tothe desired parameters and by authorized persons. It would also bedesirable that such a controller be portable and battery powered forconvenience. It would also be desirable that the controller be usablefor multiple sizes and shapes of plasma generators.

Therefore, it is an object of this invention to provide a device thatdrives non-thermal plasma emitters and controls the emitted plasma foruse in plasma medicine.

SUMMARY

This device is a power supply that drives and controls an array ofnon-thermal plasma emitters at desired frequencies and at a controlledpower level. It creates a high voltage at a high frequency. The powersupply is connected to the array with a micro-coaxial cable. The powersupply comprises a step-up transformer, a balanced driver, and acontroller. The power supply is designed such that the transformeroperates at the resonant frequency of the combined capacitance of thearray and connecting cable. The power source is preferably a battery andthe power into the array is monitored by the controller and can beadjusted by the user.

In one embodiment the balanced driver is driven directly by thecontroller. The controller monitors the phase relationship between thetransformer primary winding voltage and the gate drive voltage, andadjusts the drive frequency to resonance. In another embodiment thebalanced driver is configured as an oscillator, which drives thetransformer at resonance by default. A signal from the transformerdriver generates an interrupt to the controller for synchronizingcurrent and voltage measurements for power control.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a top view of a first embodiment of an array of non-thermalplasma emitters.

FIG. 2 is a cross-sectional view of a plasma emitter along line A-A ofFIG. 1.

FIG. 3 is a partial top view of a second embodiment of a non-thermalplasma emitters.

FIG. 4 is a partial top view of a third embodiment of a non-thermalplasma emitters without through-holes in the substrate.

FIG. 5 is a top view of a fourth embodiment of an array with a wovenarray of plasma emitters.

FIG. 6 is a schematic illustrating in perspective a portion of the wovenarray of FIG. 5.

FIG. 7 is a photograph of the first embodiment of an array with aflexible substrate and its terminal connection points.

FIG. 8 illustrates a general overview of a non-thermal plasma devicewith a controller and an external power source.

FIG. 9 is a top view of a non-thermal plasma array that is partiallycovered with a flexible sheath.

FIG. 10 is a top perspective view of rigid sheath partially covering anon-thermal plasma array.

FIG. 11 is a top view of a fifth embodiment of a non-thermal plasmaarray of the present invention in which the plasma emitters are in arectangular arrangement.

FIG. 12 is a top view of a sixth embodiment of a non-thermal plasmaarray of the present invention in which the plasma emitters are in ahexagonal arrangement.

FIG. 13 is a perspective view of a seventh embodiment illustrating anon-thermal plasma array as a tube.

FIG. 14 illustrates plasma arrays used to treat a patient's face inwhich several smaller arrays are connected to each other to effectivelycreate a larger area of plasma discharge.

FIGS. 15A-D illustrate ground electrodes having points of variousshapes.

FIG. 16 is a front perspective view of the power supply of the presentinvention connected to an array of plasma emitters, shown in a partialcut-away view.

FIG. 17 is a schematic diagram of one embodiment of the proposed powersupply.

FIG. 18 is a schematic diagram of a second embodiment of the proposedpower supply.

FIG. 19 is a cross-sectional view of a preferred embodiment of a planartransformer.

FIG. 20 is a front perspective view of an alternate power supply of thepresent invention connected to an array of plasma emitters, shown in apartial cut-away view.

FIG. 21 is a schematic diagram of a circuit for reverse power detection.

FIG. 22 is a schematic diagram of a circuit for a frequency scanfunction in the plasma driver.

FIGS. 23A-D illustrate alternate arrangements of the driver and thearray.

DETAILED DESCRIPTION

An array 100 comprises a plurality of non-thermal plasma emitters 107,disposed on a rigid or flexible substrate. The emitters 107 are arrangedsuch that when the array 100 is connected to a voltage source theemitters generate a plurality of corona discharges. The dischargesgenerate ionized gas, which in turn creates reactive species includingozone and nitric oxide.

Referring initially to FIG. 1, a non-thermal plasma array is showngenerally at 100. The array comprises a substrate 102 having at leasttwo opposing surfaces, referred to herein sometimes as a top and bottomfor convenience. A plurality of through-holes 118 is made in thesubstrate 102. A plurality of drive electrodes 110 is placed on the topof the substrate 102, with each drive electrode 110 centered over onethrough-hole 118 in the substrate 102. A plurality of ground electrodes108 is placed on the bottom of the substrate 102, with each groundelectrode 108 centered over one through-hole 118 in the substrate 102.The resulting structure of a through-hole, a ground electrode, and adrive electrode comprises a plasma emitter 107. FIG. 2 shows across-sectional view of a plasma emitter with through-holes. Each driveelectrode 110 and ground electrode 108 is generally centered on athrough-hole 118, but in certain embodiments it may be off-center. Eachelectrode's 110 shape is preferably symmetric around the through-hole118, such as a hexagon, circle, triangle, rectangle, square, or othershape, but in certain embodiments can be asymmetric. FIGS. 1 and 3illustrate an embodiment in which the drive electrode 110 is hexagonal.

FIG. 4 shows another embodiment of a non-thermal and ozone plasma array200 wherein a substrate does not have through-holes. Here a plurality ofdrive electrodes 110 is placed on the top of the substrate 102, witheach drive electrode 110 centered over a ground electrode 108 on thebottom of the substrate 102. The resulting structure of a driveelectrode on a dielectric substrate over a ground electrode is alsoreferred to herein as a plasma emitter 107.

A conductive drive track 112 on the top of the substrate 102 isconnected to at least one drive electrode 110. A conductive ground track104 on the bottom of the substrate 102 is connected to at least oneground electrode 108. One or more drive tracks 112 may be used tointerconnect as many drive electrodes 110 together as desired.Similarly, one or more ground tracks 104 may be used to interconnect asmany ground electrodes 108 together as desired. Emitters may beconnected in series or in parallel, and preferably in parallel for alower driving voltage.

A drive terminal 111 is connected to the drive track 112 and a groundterminal 106 is connected to the ground track 104. The drive electrodes110 are interconnected and connected to a drive terminal 111. Similarly,the ground electrodes are interconnected and connected to a groundterminal 106. The resultant structure is much like a printed circuitboard.

The substrate 102 is made of a dielectric material such as alumina,polycarbonate, polyimide, polyester, polytetrafluoroethylene-infusedwoven glass cloth, polypropylene, glass-reinforced epoxy laminatesheets, or the like. In certain embodiments a substrate has more thanone layer, and the layers may be made of different materials. Thesubstrate 102 is made of a rigid or a flexible material that can be madeto conform to varying surface topography and shapes such as a roughsurface, a textured surface, a smooth surface. The substrate can betwo-dimensional, such as a square, curved, rectangular, round, orhexagonal. It can also be three-dimensional such as curved, cubic,tubular, or spherical.

The substrate may also have a non-uniform shape or a non-symmetricshape. Substrates of rigid materials may be shaped to the desiredconformation before or after the plasma emitters are made therein.Substrates of flexible materials are typically conformed to the desiredshape after the array is manufactured.

In a preferred embodiment, the substrate is made of thin FR-4. At athickness of about 0.2 mm, the substrate made of FR-4 is somewhatflexible. As an alternative, the array can be fabricated from moreflexible material such as polyimide film or PTFE infused fiberglass.

Using mass manufacturing techniques, the cost of making the arrays issmall enough that the arrays can be considered consumable or disposable,simply thrown away or recycled after one or a few uses. Any polymer inthe array is consumed by the oxygen plasma, in a process commonly knownas ashing. This erosion process can be slowed by adding a thin layer ofglass on top of the entire array. A sol-gel process can be used todeposit thick layer, on the order of about a 100 nm. A thinnercrystalline layer of SiO2, Al2O3 or Y2O3 works too, and may be depositedby atomic layer deposition or plasma assisted atomic layer deposition,optionally after array burn-in for uniform plasma.

A through-hole 118 helps reduce the array capacitance and is aventilation hole for a fluid to flow from a drive electrode 110 to aground electrode 108. Such fluids include oxygen, helium, nitrogen,sulfur hexafluoride, carbon dioxide, air, and other gases. In thepreferred embodiment, the fluid is air at ambient pressure, about 1atmosphere. The oxygen in the air is ionized by the plasma generated bythe emitters 107, creating ozone. The through-holes 118 are made bydrilling, etching, cutting, laser cutting, punching, or other method. Incertain embodiments a through-hole is lined with a structure thatdirects the fluid to each electrode such as a pipe, tube, channel, orthe like. A through-hole 118 can be circular, rectangular, triangular,trapezoidal, hexagonal, or other shape.

A drive electrode 110 is capacitively coupled to ground electrode 108 ata point or points where the ground electrode touches the drive electrodesuch that when a high-enough voltage is applied to a drive electrode110, the surrounding fluid is ionized and a plasma is created, causingelectrons to flow between the drive and ground electrode.

It is desirable to have a sharp point where the plasma is generated,since this is used to help initiate the plasma. The sharp points maytake any form, such as a sharp point, a blunt point, a spear point aradius, or the like. FIG. 3 illustrates an embodiment in which theground electrode 108 is a star with six sharp points 120. FIG. 4illustrates an embodiment in which the ground electrode 108 is atriangle with three sharp points 120. FIG. 15A illustrates an electrodewith six sharp points; FIG. 15B shows blunt points; FIG. 15C shows spearpoints; and FIG. 15D shows radius points.

A drive electrode 110, drive track 112, ground electrode 108 and aground track 104 can be printed, etched, laminated, or otherwisedisposed onto the substrate 102. They can be made of copper, silver,nickel, or any other conductive material. The can be insulated, such asby a solder mask, polyester film such as Mylar®, mica, polypropylene,polytetrafluoroethylene such as Teflon®, or the like, and in otherembodiments are not insulated. For manufacturing convenience, preferablythe drive electrode 110 and ground drive 112 are made of the samematerial and disposed onto the substrate 102 at the same time.Similarly, preferably the ground electrode 108 and ground track 104 aremade of the same material and disposed onto the substrate 102 at thesame time. Alternatively the drive electrode 110, drive track 112,ground electrode 108 and a ground track 104 are made of differentmaterials and may be disposed on the substrate in processes occurring atthe same or different times.

FIGS. 5 and 6 show another embodiment of a non-thermal array 100 whereina plurality of plasma emitters 107 is created at the intersections ofwires that are woven together. The wires 410 of drive electrode 408 arewoven with the wires 406 of ground electrode 404 to form a woven array.One electrode is connected to a plurality of insulated wires and theother connected to a plurality of uninsulated wires. If the wireinsulation is a polymer, a coating, such as SiO2, is preferred toprevent ashing. The air in the interstitial space between the wires isignited to form a plasma. Wires can be copper, silver, nickel, or anyother conductive material. The wires are insulated with non-conductiveor dielectric materials such as plastic, rubber-like polymers, orvarnish. In FIG. 5 the emitters 107 are covered by a rigid sheath 520having hexagonal apertures 521.

The drive terminal 111 and ground terminal 106 are printed, cut,punched, laminated, etched, connected, or otherwise attached to thedrive track 112 and ground track 104, respectively. There are at leastthose two terminals for each array of emitters, but there may be as manyterminals as desired. For example, there may be two terminals for eachemitter 107, or there may be more than two terminals for each emitter107, for example if extra terminals are desired for redundancy in caseof failure, or to have better placement for connection to the voltagesource. Preferably the terminals 111 and 106 are attached to or integralwith the substrate, such as with solder pads, banana plugs, ringterminals, spade terminals, pin terminals, or the like.

The emitters 107 can be arranged in a variety of relative positions,such as lines, concentric circles, random placement, etc. Thearrangement of emitters is sometimes referred to herein as an array. Anarray can take on any shape to fit the user's needs. Typically thearrangement of the emitters 107 is generally symmetrical, such as arectangle or hexagon, but the arrangement can be non-symmetrical too,which can be useful for using a single substrate target separate areaswith different concentrations of plasma. FIG. 1 illustrates the emitters107 arranged in rows, and each row is offset from the previous row. Thissame pattern is repeated with as many rows as the user needs to form thedesired size of the array. The rows illustrated in FIG. 1 have 8emitters each, but any number of emitters can be used in each row. Therows illustrated in FIG. 7 have 8 emitters each, but any number ofemitters can be used in each row.

The size of the array ranges from microscopic to macroscopic and, whiletheoretically unlimited, in practice is limited by manufacturingtechniques. In practice, the arrays are typically less than 5 inches inany dimension. If a larger area of plasma discharge is desired, smallerarrays can be placed side-by-side and connected to each other toeffectively create a larger array controlled as a single array. FIG. 14illustrates plasma arrays 100 used to treat a patient's face in whichseveral smaller arrays are connected to each other to effectively createa larger area of plasma discharge. In other cases, the smaller arraysare placed sized-by-side to create a larger array, but are not connectedto each other so that they can be controlled independently.

Plasmas can be defined in a number of characteristics including size(typically in meters), lifetime (seconds), density (particles per cubicmeter) and temperature. In certain embodiments a first emitter 107 has adifferent plasma strength than a second emitter 107. The plasma strengthis determined by a number of factors including dielectric thickness,drive voltage (which determines the duty cycle in which the plasma isignited and retained), and atmospheric pressure. Typically the resultantplasma is fan shaped, extending about 0.8 mm from the point and about120 degrees of fan.

FIG. 7 shows a non-thermal plasma array 100 in which an insulative layer304 is attached to the substrate 102, under the ground terminal 106 anddriver terminal 111. The insulative layer 304 can be neoprene, polymercoating, Mylar®, Teflon®, or the like.

FIG. 9 shows a non-thermal plasma array 100 with a sheath 520 coveringat the plasma emitters. In some embodiments only some of the emittersare covered. In a preferred embodiment the sheath 520 is an electricalinsulator that acts as a barrier between the array and a surface ofinterest. The electrical insulator 520 allows plasma generated from thearray to effect and react with a surface of interest, but does not allowfluids to permeate thru the cover to the created plasma, and surface ofa substrate. Thus it is breathable to gaseous molecules, protects a useror surface from possible electrical shocks, and prevents liquids fromgetting to the electrodes that might cause electrical shorts. Preferablythe sheath 520 is flexible and made of polytetrafluoroethylene (“PTFE”),which provides a water-resistant yet breathable covering. Flexiblesheaths can also be made of expanded polytetrafluoroethylene, neoprene,hydrophobic polyester, hydrophilic polyester, or the like. FIG. 10 showsone embodiment of a rigid sheath 520 with apertures 521 centered on thethrough-holes 118 that are on the non-thermal plasma array 100. Thesheath 520 can vary in length, width, and height to fit a non-thermalplasma array's size and shape. Typically the sheath is also removable.

A non-thermal plasma array 100 can conform to any shape or size, sizefor treating human diseases in various anatomical locations such as atoe, ear, finger, face, etc. FIGS. 11, 12 and 13 show examples ofadditional embodiments of the array 100. FIG. 11 shows a rectangulararray 100 of plasma emitters 107 in which one side of the array issubstantially longer than the other side. This arrangement may beparticularly useful for the treatment of large narrow surface areas.FIG. 12 shows a hexagonal array 100 of plasma emitters 107. FIG. 13shows an array 100 formed into a tube, with plasma emitters arrangedalong the surface of the tube. This arrangement may be particularlyuseful for the treatment of tubular-shaped areas such as fingers so thatthe inside of the tube stays in contact with the outside of the finger.This arrangement may also be particularly useful for treating the insidesurface of a tubular human body part such as an ear canal in which theoutside of the tube stays in contact with the inner surface of the earcanal. The tubular array 100 can be pre-formed on a rigid or flexiblesubstrate. Alternatively, a rectangular array 100 on a flexiblesubstrate can be bent into a tube at the time of treatment.

To create the plasma, a voltage is applied to one or more driveelectrodes 110 with a power supply 500, sometimes also referred toherein as a driver. It creates a high voltage at a high frequency. Withthe drive electrodes 110 at a high potential relative to the groundelectrode 108, current flows through the drive electrodes 110 andthrough a fluid in the through-hole 118 and around the array. The fluidis ionized to create a plasma region around each drive electrode 110,ground electrode 108 or both. The ions from the ionized fluid pass acharge to a plurality of ground electrodes 108 or to an area of lowerpotential. In a preferred embodiment the power supply 500 drives andcontrols an array 100 of non-thermal plasma emitters at desiredfrequencies at a controlled power level. The power supply 500 isconnected by wire or wirelessly to a controller 204. The controller 204controls the functionality of the array 100 such as time on/off,strength of plasma, strength of a plasma field from electrode toelectrode, frequency, power, and the like. The characteristics of thepower supply will depend largely on the size of the array.

The power supply 500 is connected to the array 100 with a micro-coaxialcable, leads 502, or other connector, referred to herein generally as acable 202. See FIG. 16. The power supply 500 comprises a step-uptransformer 201, a balanced driver, and a controller 204. See FIG. 17.The power supply 500 further comprises a power source 506, which ispreferably a battery. The power into the array is monitored by thecontroller 204 and can be adjusted by the user.

The inductance of the transformer's secondary winding and the combinedcapacitance of the array and cable form a parallel LC circuit with aparticular resonant frequency. This arrangement takes advantage of theresonance phenomenon that occurs when a vibrating system or externalforce, such as the power supply 500, drives another system, such as thearray 100, to oscillate with greater amplitude at a specificpreferential frequency. The modulation frequency could be set manually.However, since the resonant circuit Q factor is relatively high (above300), so that the range of frequencies the device resonates at isrelatively small, an automatic tuning mechanism is preferred forreliable operation. This is done by monitoring the phase relationshipbetween voltage and current on the primary winding to determine when thetransformer is operating at resonance. In a preferred embodiment, thedrive frequency is in the 100 kHz range to allow a relatively wide rangeof modulation frequencies. However, the described invention couldoperate over a very wide range, 10 kHz to over 10 MHz, depending on thedriving electronics.

The preferred embodiment will resonate at the combined capacitance ofthe array 100 and the cable 202 with a tuned step-up transformer togenerate high voltage AC at the array 100. The high Q of the tunedcircuit produces a clean sinusoidal drive waveform to minimize harmonicradiation and provides a voltage boost. The controller 204 adjusts thetransformer drive frequency to the resonant frequency of the tunedcircuit. The resultant plasma frequency typically remains steady and ispulsed to create a modulated therapeutic frequency. However, thetransformer secondary or primary voltage can also be monitored as themodulation frequency is adjusted, to detect a change in breakdownvoltage versus modulation frequency. This may be used to adjust themodulation frequency for maximum therapeutic effect.

The input power used for the array driver is typically DC although thearray itself intrinsically requires AC. The power supply 500 converts DCto AC. Typically the plasma frequency will operate at given frequencybetween about 50-100 kHz. In a preferred embodiment, the AC voltageapplied to the drive electrodes is modulated in pulses, typically at afrequency between above 0 Hz to about 10 kHz. Modulation is done byturning this frequency on and off, i.e. generating the modulationdigitally by pulse-width modulation of the transformer primary drivewaveforms. This could be square wave modulation, or other waveform typesuch as sine wave. For example, for a plasma frequency of 50 Hz, thearray emits periodic bursts of 50 Hz energy. Alternatively a continuouswave voltage is applied to the drive electrodes.

Correlation has been observed between modulation frequency andbiological effects. A modulation frequency scan function in the plasmadriver can use the relative plasma power measurement to determine theoptimal modulation frequency for treating a particular condition, or formeasuring the progress of a treatment. To obtain more detailedinformation between the biological interaction with the plasma array, asearch is conducted for radio signals in the range of the oxygen masermechanism. See FIG. 22.

If a therapeutic plasma frequency is found, the plasma frequency can beadjusted by adding parallel capacitance of an appropriate value. Sincethe voltage is about 1 kV RMS, this is typically done by switching highvoltage capacitors with a relay. A practical solution would typicallyuse a set of seven binary related values. The AC drive voltage can alsobe modulated if a therapeutic modulation frequency is found. This wouldtypically be done be adjusting timer values in the digital controller inthe driver.

A preferred embodiment monitors transformer primary voltage and current,using this data for power control and for hardware interlock to mitigateagainst catastrophic failure of the electronics. Excessive power willshorten the life of the array. Since the array will eventually fail fromerosion of the dielectric, fast current limiting will allow a gracefuland safe end of operation.

FIG. 18 shows a typical system level block diagram. Array 100 isconnected to the power supply 500 with cable 202, preferably using aconnector (as opposed to hard-wired) so that the cable can be easilyremoved and reused in the case of eventual array failure. Cable 202preferably has connectors on both ends. Transformer 703 provides thehigh voltage for the plasma array 100. Resistor 705 provides a highvoltage monitor point for secondary voltage monitor 706. Secondarycurrent monitor 704 connects to the cold side of the transformersecondary.

In a preferred embodiment, a variable voltage power source 506 isconnected to the transformer primary center tap, and a pair of MOSFETs708 provide balanced drive to the primary winding of transformer 703.Primary voltage and current amplitude and phase monitors 709 are used bycontroller 204 to provide the appropriate duty cycle and frequency forthe transformer.

In an alternative embodiment, the transformer driver can be configuredas an oscillator, so the transformer operates at the resonant frequencyby default. In this case, a signal from the transformer driver is sentto the controller to synchronize the measurement of voltages andcurrents. This is can be used for accurate power measurement, forinstance.

In another embodiment, the power supply 500 comprises a resonanttransformer 201, with a half bridge driver on the transformer primary.See FIG. 17. The transformer primary bias is derived from a boostconverter 212, which is connected to a power source. The power sourcecan be internal to the power supply, such as a battery 208, or externalto it such as a cell phone charger connected to mains power, or avehicle power outlet. For precise power monitoring, the transformersecondary voltage is monitored through capacitors 205 and 206. Thesecondary current is monitored through sense resistor 207.

In one example, a typical large array (for example an array with closelyspaced emitters in an area of about 2.5 inches by 6 inches) combinedwith a 4 foot length of RG-178 coaxial cable will have a typicalcapacitance of 720 pF. The step-up transformer 201 resonates with acapacitive load consisting of the coaxial cable 202 and the planarmicro-plasma array 100. The main power source is a rechargeable lithiumbattery 208. This is charged through USB connector 223, which also is anexternal data interface to controller 204.

To allow the array power to be rapidly shut off in the case ofover-current caused by array failure, the boost converter 212 switchingelement is driven by the controller 204. Capacitor 211 provides chargestorage for high current pulses through the boost inductor 212.Switching element 213 may be driven through an amplifier to obtainadditional drive current and/or voltage. The boosted flyback voltage isrectified by diode 214 and filtered by capacitor 215. Resistor 216 dropsthe voltage to a suitable range for the controller 204.

Inductor 217 is optional, but allows a higher duty cycle on the driveswitching elements 218, reducing switching element loss while improvingthe spectral purity of the transformer output for EMC compatibility. Thetransformer primary voltage is sampled through resistor 219 to determinethe transformer resonant frequency in auto-tuning mode.

The preferred embodiment uses a planar transformer with “EI” type core.See FIG. 19. The “I” side 601 is placed at the top, away from thewinding PCB 603. The “E” side 602 is placed at the bottom. This placesthe air gap 604, used to set the transformer inductance, to the toprather than the middle of the core. The magnetic flux concentratedaround the air gap will increase AC loss, so the transformer windings,particularly the primary winding, are placed as far as possible from theair gap. A typical transformer design uses a planar ferrite core with a12 layer FR-4 PCB. With a 135:1:1 turns ratio, a typical large arraywill operate at 50 kHz with an air gap A_(L) value of 700 nH/N².

The preferred embodiment uses a controller, such as a microcontroller,FPGA or CPLD, to directly control the current switching on thetransformer primary winding. This is typically between 50 kHz and 500kHz, using a pair of N-channel MOSFETs. A buffer amplifier may be usedto increase the gate drive voltage and/or current. The advantage of thisarrangement is the ability of the controller to instantly stop switchingin the event of an over-current condition caused by array failure.

The preferred embodiment is powered from lithium cells, with a supplyvoltage between 2.8 and 4.2V. See FIG. 17. The transformer primarycenter tap voltage is derived from a boost converter 212, with currentbeing switched using a N-channel MOSFET. A buffer amplifier may be usedto increase the gate drive voltage and/or current. In the preferredembodiment, the duty cycle of each transformer FET is 50%, operating ina balanced configuration. The boost converter 212 is operated at twicethe frequency of the transformer drive, and is driven by the controller204. Any ripple on the transformer center tap will be the sameinstantaneous value for either side being switched.

An alternate embodiment connects the transformer primary balanced driverin a cross connected feedback such that the driver automaticallyoperates at the transformer resonant frequency. However, this requiresadditional electronic components to allow rapid shutdown,synchronization with the boost converter, and synchronization with thecontroller. In a typical embodiment, interrupt signals to the controllerwould be generated by both legs of the transformer primary.

In the preferred embodiment, the controller determines the transformerresonant frequency as follows. In this auto-tuning mode, the controllerreduces the transformer drive duty cycle to a small value to protect theelectronics. With a step-up transformer having a secondary winding withmore turns than its primary winding, the output voltage is increased.For a given drive frequency, the controller measures the plasma drivevoltage on the transformer secondary. If the voltage phase on thetransformer primary leads the drive signal, the frequency is too high.The controller performs a frequency sweep to find the highest resonantpeak. An alternate method is to compare the waveform on one leg of thetransformer primary with the corresponding gate drive waveform, andadjust the drive frequency in a binary search to determine the frequencyfor switching at zero crossing. This will occur at the transformerresonant frequency.

Drive power into the array 100 is determined by measurements of voltageand current on the transformer secondary. The plasma initiation voltageis influenced by humidity and air pressure, so an accurate voltagemeasurement is desirable. In the preferred embodiment, transformersecondary current is sensed across a low value resistor.

An alternate method of measuring the plasma power in the array is tomeasure the reflected (“reverse”) power at a high harmonic frequency.Since the plasma array has a high AC voltage across a relatively largecapacitance, the amount of reactive power in the dielectric is verylarge compared to the amount of real power in the plasma. Therefore,measuring real power dissipation in the plasma is very difficult ifmeasured at the fundamental drive frequency. Because the I/V curve ofthe plasma is nonlinear, while the capacitance of the array isrelatively flat versus voltage, the measurement is much easier at a highharmonic of the drive frequency. A practical measurement frequency is10.7 MHz because of the availability of inexpensive ceramic filters.This also reduces the size of components in the resonant circuits.Precise tuning is required, so the inductors preferably havenon-magnetic cores for tighter tolerance. This simplifies the problem ofisolating the large reactive component of the array load, and any powerloss from dielectric heating in the array, from the effect of theplasma. A typical embodiment will use parallel resonant element tuned LCcircuit 701 to block energy from the driver at 10.7 MHz. See FIG. 21.Series resonant element tuned LC circuit 702 provides a low impedancecurrent return at 10.7 MHz. Transformer 703 provides high voltageisolation and performs current to voltage conversion at 10.7 MHz. Filter714 blocks harmonics from the driver that are not blocked by theresonant circuits. Detector 715 is preferably a logarithmic detector toallow measurement over a large power range. Because of the interwindingcapacitance of the high voltage transformer which can pass harmonicenergy at 10.7 MHz, a parallel tuned LC circuit 701 is used to blockthis. Series tuned LC circuit 702 provides a low impedance at 10.7 MHz,which allows current measurement through transformer 703. The capacitorin the series tuned LC circuit 702 will typically be rated at 1.5 kV. Ina typical embodiment, transformer 703 is bifilar wound PTFE insulatedwire around a ferrite bar. Since isolation of 1 kV AC is required, thewindings are typically covered by insulating varnish to prevent airdischarge between windings. Filter 714 is needed to remove harmonicenergy that is not blocked by the tuned circuits. Detector 715 istypically a log detector. When a means of measuring the relative levelof high harmonic reverse power at a high resolution is provided in theplasma driver, it can be used to set a constant plasma power levelregardless of humidity or air pressure.

In a stand-alone driver, a housing 501 contains the power supply 500, auser interface 222, one or more inputs to the power supply, and one ormore outputs to the array. See FIG. 16. Inputs include a USB port 223,an HMDI port, a headphone jack 224, a micro-USB jack, a lightening jack,and touch buttons or a touchscreen. Outputs to the array include aheadphone jack 224, a micro-USB jack, a lightening jack, and multi-pinjacks. An audio transducer may be used to aid the visually impaired. Ina wearable application, a vibrator may be added for discrete userfeedback. In a battery-powered device, the housing also contains thebattery, which may be either a primary or rechargeable battery. Anembodiment connecting through USB may not need a battery, because theUSB port may be used for input and battery charging.

The user interface will typically be a small LCD display 222. Bluetoothhardware can also be added for convenient connection to a smartphone.The controller 204 is connected to the user interface 222. In apreferred embodiment, a multicolor LED will indicate operating modes,including battery charging. While some embodiments of the driver usepre-programmed memory so that operating parameters that cannot bechanged, other embodiments are programmable. The inputs can be used toprogram plasma operating parameters such as operating time and powerlevel. The USB connection can also be used to set up additional featuressuch as WiFi connection to a defined SSID and network password. However,a user's complete freedom to control the array 100 may not be the bestsolution for all embodiments.

In a preferred embodiment, the device is configured to emit plasma in aprescribed a treatment protocol provided by a physician, pharmacist, orclinician, much like a conventional prescription for medicines used withother drug delivery devices. The device may also retrieve patientinformation. The driver and array can be configured in a number of waysto do so. See FIG. 23A-D. In general, the prescriber connects a low-costadapter board or dongle to a computing device. A software applicationrunning on the computing device performs authentication, loads recordeddata, and programs the prescription. Data from treatments is recorded onthe adapter board or dongle for upload to a computing device after thetreatment. This data can be used post-treatment to determine efficacyand verify that the prescription was applied. For better control, and topromote a controlled business model, prescribers can be limited todownloading prescriptions from a central database rather than enteringthem directly.

In one embodiment a mobile computing device 610 is connected to anadapter board 225, which in turn is connected to a dongle 220 that isconnected by cable 202 to the array. See FIG. 23A. Adapter board 225functions as a physician's prescription book which containsauthentication code registered per physician, clinician, pharmacist orpharmacy. Adapter board 225 is also a gatekeeper between encryptedprotocols and user's privacy data being uploaded and downloaded fromdongle 220. The adapter board 225 has an MCU onboard to interfacebetween the dongle 220 and proprietary software applications installedon a mobile computing device or a desktop computer.

The dongle 220 includes settings for power, modulation details and timeof a desired treatment. Thus the dongle 220 can be programmed with atreatment prescription for use with a driver. The dongle 220 may includean identification feature that is ensures that the driver is being usedwith the array of the appropriate size or shape for the desiredtreatment or patient. In a preferred embodiment the identificationfeature is a chip encoded with an embedded code that acts as anauthentication handshake between the array 100 and the dongle 220 tomake sure that only authorized arrays are used with a given powersupply. In another embodiment the connector on the array has a physicalshape mated to the connector on the power supply such that only deviceswith matching connectors operate to generate a plasma.

To ensure the array emits energy at the desired parameters, in apreferred embodiment the array will work only if its embeddedidentification code matches the dongle. For example, a programmed dongle220 and its mated array may be given to a patient with the patient'sprescription. The patient then attaches the dongle 220 to a powersupply, whether it is a specialized device or a mobile computing device,and powers the plasma array to treat with plasma energy. Without therequired code, the array will not be operational. Thus, the drivers canbe sold with no prescription over the counter, much like fabric bandagessuch as BandAids®, and mated with a prescription dongle 220 and arraywhen needed. Physicians and pharmacists may program the dongle 220directly with customized protocols or they may program them with commonprotocols stored in a centralized prescription database. The dongle 220can be programmed to record parameters of the treatment which may beevaluated post-treatment to verify that the prescription was applied andto judge its efficacy. See examples below.

In another embodiment, the mobile computing device 610 is connected tothe adapter board 225, which in turn is connected to a cable 202 that isconnected to the array. The function of the dongle, namely theprescription, is embedded on the array or in the cable. The integrationof the dongle function onto the array 100 is referred to herein as asmart array 203. See FIG. 23B. Flash memory can be used to store thedesired data on the array or in the cable. This may require a customcable, but would allow a temperature sensor on the array as well. Thismay be important for some diabetic patients or others who have lostsensation and are insensitive to heat. Another alternate embodiment usesthe memory of the mobile or desktop computing device.

In another embodiment, the driver 500 is connected to the dongle 220,which is connected by cable 202 to an array. See FIG. 23C. If using asmart array, the driver can be connected directly to it with a cable.See FIG. 23 D.

Typically the mobile computing device is connected to the array 100using its headphone jack 224 or USB port, but may be connected with acustom interface. Mobile computing devices include a smartphone 606,laptop computer 607, or tablet. On FIG. 20 the dashed line indicatesthat either the phone or laptop may be connected to the adapter boardand the array. A desktop computer may also be used to powering andcontrolling the array. Mobile and desktop computing devices areprogrammable using onboard memory with a downloaded mobile applicationor installed program.

Plasma devices of the present invention can be used for treating manytypes of surfaces for purposes including cleaning, decontaminating,sterilization, and healing. For example:

Example 1: Decontamination of a Cell Phone

Individuals take cell phones where everywhere they go and are constantlyusing it after using the restroom, touching dirty door knobs, shakingothers' hands, sharing the phone with others, and touching money. Allthese items are full of bacteria, which can spread to the individual'scell phone. Consequently, cell phones have up to 18 times more bacteriathan a public restroom. In certain embodiments a non-thermal array 100or smart array 203 can be placed around or incorporated into a cellphone. Once the non-thermal array 100 or smart array 203 is turned onthe microorganisms on the phone will be inactivated, in effectsanitizing the cell phone from any infectious agents.

Example 2: Biological Warfare Decontamination Suit

In war biological weapons may be used against soldiers. In certainembodiments a biological warfare suit can be lined with non-thermalplasma arrays 100 or smart arrays 203. When a soldier has beencontaminated with a biological weapon, the soldier can put on thenon-thermal-plasma lined suit. Once the suit is on, the arrays 100 areturned on and the soldier can be decontaminated. The suit is reusable.

Example 3: Killing Fungus or Bacteria with a Non-Thermal Plasma Device

A voltage supplied to a plasma array can be modulated (pulsed or keyedon and off) at a rate of about 1 Hz to about 10 kHz. Specific modulationfrequencies (the so-called Rife frequencies) have therapeutic effects inwhich a specific frequency is correlated to kill a specificmicroorganisms, including forms of bacteria, virus, fungus, mold, etc.The controller can use these frequencies to produce biological effectsbeyond those produced by reactive oxygen species and reactive nitrogenspecies. The resulting biological effects created by a non-thermalplasma array over a large surface area can eliminate microorganisms onany surface type.

Example 4: Method for Creating Ozone

Ozone is an unstable, but highly beneficial molecule, and is created byplasma. Plasma is a mixture of neutral and charged particles. When avoltage is applied to an array 100 of plasma emitters 107 that are in agas containing oxygen, the plasma emitters generate a transfer ofelectrons that generates ozone. Ozone can be applied to a human body fortherapeutic effects, to water for oxidizing pathogens and syntheticsresidues in the body, and to olive oil for ingesting which gives anindividual a steady internal application of ozone. In addition, ozonecan be used as an air disinfectant killing germs, infectiousmicroorganisms, and neutralizing many biological problems like bacteria,viruses, mold and chemical outgassing.

Example 5: Cosmetic Treatments

Nitric oxide is a free-radical that has been shown to be beneficial intreating photodamaged facial skin by burning the old damaged skin cellsso they can be sloughed off and replaced with new, healthy skin cells.An array of plasma emitters that are in a gas containing nitrogen areplaced on the desired treatment area of the skin and the plasma emittersgenerate nitric oxide across the entire treatment area. In this wastreatment using the present device is much faster than the conventionalmethod of treating the area with plasma plume that is repeatedly passed,or scanned, across the treatment area.

Example 6—Treating Pseudomonas aeruginosa

In one example a power supply is used in conjunction with an array totreat a patient who has Pseudomonas aeruginosa, a multidrug-resistantpathogen, on her foot. A physician prescribes plasma treatment of 241 Hzfor 10 minutes, twice a day for seven days. The pharmacist receives theprescription per treatment from physician, connects an adapter board 225to a desktop computer, and programs the dongle 220 directly with anauthentication code and instructions to operate the plasma-emitter arrayat 241 Hz for 10 minutes. The patient obtains the programmed dongle andmated array, or smart array 203, from the pharmacist, attaches it to apower supply such as a cell phone charger. The patient places the arrayon her foot where the infection is. The power supply confirms that ithas been attached to an authorized array and initiates treatment. Thepatient leaves the array in place for the 10 minute treatment durationper the programmed protocol. When the 10 minutes has elapsed the patientremoves the array from her foot. The patient repeats the treatment twicea day for six more days. The dongle and array, or smart array, can bereturned to the pharmacist for uploading usage data of past treatmentsand reprogramed with new protocols for re-use.

Example 7—Treating Candida albicans

In another example a power supply is used in conjunction with an arrayto treat a patient who has Candida albicans, a fungal infectiontypically of the mouth or genitals. A physician prescribes plasmatreatment of 482 Hz for 10 minutes, applied twice a day for seven days.The pharmacist receives the prescription, connects an adapter board 225to a desktop computer, and programs the dongle 220 directly with anauthentication code, and instructions to operate the plasma-emitterarray at 482 Hz for 10 minutes. The patient obtains the programmeddongle, cable and attached plasma array from the pharmacist, andattaches it to a driver. The driver is portable and chargeable using anUSB wall charger. The driver confirms that it has been attached to anauthorized array and initiates treatment. The patient leaves the arrayin place for the 10 minute treatment duration. When the 10 minutes haselapsed the patient removes the array from her mouth. The patientrepeats the treatment once a day for six more days. The dongle andarray, or smart array, can be returned to the pharmacist for uploadingusage data of past treatments and reprogramed with new protocols forre-use.

Example 8—Treating Trichophyton rubrum

In another example a power supply is used in conjunction with an arrayto treat a patient who has Trichophyton rubrum, a fungus that is themost common cause of athlete's foot, fungal infection of toenails, jockitch, and ringworm. The treatment is 775 Hz for 10 minutes, for threetreatments per day, until the symptoms go away. The patient purchasesover-the-counter a power supply, dongle and arrays that are customizedto provide a limited number of treatments. For example, for toenailfungus, the patient purchases a device that can provide up to twenty 10minute treatments of plasma at 775 Hz. The patient applies the plasmaarray to his infected toenail for 10 minutes each day until the symptomsgo away.

Example 8—Treating Trichophyton metagrophyte

In another example a plugged cable is used in conjunction with an arrayto treat Trichophyton metagrophyte, another cause of various human skininfections and also of a skin infection in mice. A dongle is programmedusing a desktop computer connected to an adapter board that has accessto the internet. An authorized user downloads a protocol from atreatment database to the dongle then causes the power supply to provideplasma treatments at a given time, frequency, and duration such as 775Hz for up to 10 minutes per treatment, three times per day for 4 weeks.The dongle and array, or smart array, can be returned to the pharmacistfor uploading usage data of past treatments and reprogramed with newprotocols for re-use.

While there has been illustrated and described what is at presentconsidered to be the preferred embodiments of the present invention, itwill be understood by those skilled in the art that various changes andmodifications may be made and equivalents may be substituted forelements thereof without departing from the true scope of the invention.The embodiments of the invention described herein are not intended to beexhaustive or to limit the invention to precise forms disclosed. Rather,the embodiments selected for description have been chosen to enable oneskilled in the art to practice the invention. Therefore, it is intendedthat this invention not be limited to the particular embodimentsdisclosed, but that the invention includes all embodiments fallingwithin the scope of the appended claims.

We claim:
 1. A device for controlling an array of non-thermal plasmaemitters, the array having a capacitance, the device comprising: a powersupply connectable to the array with a cable having a capacitance,wherein the sum of the capacitance of the array and the capacitance ofthe cable is a combined capacitance; the power supply operates at theresonant frequency of the combined capacitance; and an identificationfeature that permits the device to operate only authorized arrays. 2.The device of claim 1 wherein the power supply comprises: a. acontroller; b. a step-up transformer; and c. a balanced driver.
 3. Thedevice of claim 1 further comprising memory for storing one or moreparameters for operation of the array.
 4. The device according to claim1 wherein the power supply further comprises a battery.
 5. The deviceaccording to claim 1 wherein power supply further comprises a powersource, and the power source and controller are in a mobile computingdevice.
 6. The device of claim 1 wherein the array comprises a flexiblesubstrate.
 7. A device for controlling an array of non-thermal plasmaemitters, the array having a capacitance, the device comprising: a. apower supply comprising: b. a controller; c. a step-up transformerhaving a primary winding and a secondary winding; d. a balanced driver;and e. a cable connecting the power supply to the array, the cablehaving a capacitance; wherein the controller measures the voltage on theprimary winding and compares it to the voltage on the secondary windingto determine a resonant frequency of the device.
 8. The device of claim7 wherein the resonant frequency is sum of the capacitance of the arrayand the capacitance of the cable.
 9. The device of claim 7 furthercomprising memory for storing one or more parameters for operation ofthe array.
 10. A device for controlling an array of non-thermal plasmaemitters, the array having a capacitance, the device comprising: a. amobile computing device connectable to the array using a cable having acapacitance; b. a controller and a power source in the mobile computingdevice; and c. an identification feature that permits the mobilecomputing device to operate only authorized arrays.
 11. The device ofclaim 10 wherein the sum of the capacitance of the array and thecapacitance of the cable is a combined capacitance and the power sourceoperates at the resonant frequency of the combined capacitance.
 12. Thedevice of claim 10 further comprising memory for storing one or moreparameters for operation of the array.
 13. The device of claim 12wherein the memory is in the mobile computing device and isprogrammable.
 14. The device of claim 10 wherein the identificationfeature is embedded in a dongle disposed on the cable.
 15. A device forcontrolling an array of non-thermal plasma emitters, the array having acapacitance, the device comprising: a. a housing comprising: i. userinterface; ii. one or more inputs; iii. one or more outputs; iv. a powersupply, wherein the power supply comprises: a. a controller, b. astep-up transformer having a primary winding and a secondary winding,and c. a balanced driver; v. memory for storing one or more parametersfor operation of the array; and b. a cable connecting the housing at anoutput to the array, the cable having a capacitance; wherein the sum ofthe capacitance of the array and the capacitance of the cable is acombined capacitance; and wherein the power supply operates at aresonant frequency of the combined capacitance.
 16. The device of claim15 further comprising an identification feature that permits the powersupply to operate only authorized arrays.
 17. The device of claim 15wherein the controller measures the voltage on the primary winding andcompares it to the voltage on the secondary winding to determine theresonant frequency.
 18. The device of claim 15 wherein the memory isprogrammable via an input.